title: Diagnostic precision of retinal nerve fiber layer and macular thickness asymmetry parameters for identifying early primary open-angle glaucoma.
abstract: OBJECTIVE
  To evaluate the diagnostic capabilities of intereye and intraeye differences in retinal nerve fiber layer (RNFL) thickness and macular thickness for identifying early primary open-angle glaucoma (POAG).
  
  
  METHODS
  Prospective, cross-sectional cohort study.
  
  
  METHODS
  All subjects were enrolled from an ongoing institutional glaucoma study. We used spectral-domain optical coherence tomography (Spectralis; Heidelberg Engineering) to obtain macular thickness (posterior pole asymmetry scan) and RNFL thickness (circumpapillary scan) in both eyes of 50 early POAG and 50 control subjects. Early POAG subjects had glaucomatous optic neuropathy with mild, reproducible visual field loss in at least 1 eye, and control subjects had normal intraocular pressures, visual fields, and optic nerves. We recorded total, superior, and inferior RNFL and macular thicknesses and then calculated intereye and intraeye differences (asymmetry parameters). Statistical evaluation included receiver operating characteristic and multivariate logistic regression analyses.
  
  
  RESULTS
  Intereye macular thickness asymmetry had the highest diagnostic sensitivity (88% at 80% specificity; 83% at 95% specificity), followed by total RNFL thickness (88% at 80% specificity; 75% at 95% specificity). Parameters with the largest areas under the receiver operating characteristic curves were: total RNFL thickness (0.937), intereye RNFL asymmetry (0.921), intereye macular thickness asymmetry (0.913), inferior RNFL thickness (0.905), superior RNFL thickness (0.887), intereye inferior macular thickness asymmetry (0.872), and intraeye macular thickness asymmetry (0.860). These 7 values were not significantly different. In multivariate logistic regression analyses, intraeye macular thickness asymmetry, intereye macular thickness asymmetry, intereye RNFL thickness asymmetry, and total RNFL thickness were related independently to early POAG.
  
  
  CONCLUSIONS
  Structural asymmetry parameters performed well, identifying early POAG as well as RNFL thickness. Further study is indicated to validate these results.
authors.affiliation: New Mexico Veterans Administration Health Care System, Albuquerque, New Mexico. Electronic address: Michael.Sullivan-Mee@va.gov.
authors.forename: Michael
authors.initials: M
authors.lastname: Sullivan-Mee
authors.affiliation: New Mexico Veterans Administration Health Care System, Albuquerque, New Mexico.
authors.forename: Claudia C
authors.initials: CC
authors.lastname: Ruegg
authors.affiliation: New Mexico Veterans Administration Health Care System, Albuquerque, New Mexico.
authors.forename: Denise
authors.initials: D
authors.lastname: Pensyl
authors.affiliation: New Mexico Veterans Administration Health Care System, Albuquerque, New Mexico.
authors.forename: Kathy
authors.initials: K
authors.lastname: Halverson
authors.affiliation: New Mexico Veterans Administration Health Care System, Albuquerque, New Mexico; Department of Mathematics and Statistics, University of New Mexico, Albuquerque, New Mexico.
authors.forename: Clifford
authors.initials: C
authors.lastname: Qualls
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008266:Macula Lutea / Q000473:pathology*; D008297:Male; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence; D014786:Vision Disorders / Q000175:diagnosis; D058609:Visual Field Tests; D014794:Visual Fields